In general, most conventional pneumatic tools are driven by inputting a pressurized gas through an air supply pipe connected to the pneumatic tool by an appropriate detachable air nozzle. Further, the air nozzle is connected to a handle of the pneumatic tool by a screwing method or other fixing method.
However, these conventional pneumatic tools usually have a drawback, since the air supply pipe is made of a hard and solid material and generally connected to the air nozzle, therefore the air supply pipe of the pneumatic tool cannot be rotated independently. As a result, when the pneumatic tool is rotated, an adjacent pipe section of the air supply pipe winds around the pneumatic tool, which will reduce the flexibility of controlling the pneumatic tool. In addition, the wound air supply pipe will reduce the pressurized gas supply and affect the operating quality of the pneumatic tool.
Please refer to the R.O.C. Patent No. 333485 entitled “Device, throttle and air bushing for pneumatic tools”, which disclosed a rotary air bushing for rotating and connecting a pneumatic tool to a pressurized gas supply tube. The air bushing comprises a first groove formed on the external surface of the air bushing and a pillar being inserted inside the handle of the pneumatic tool to cope with its rotation. Such structure allows the air bushing to rotate along the vertical axis inside the handle of the pneumatic tool. When the soft air supply tube is connected to the outer end of the air bushing, the pneumatic tool can rotate independently.
However, this prior art needs to have a hole on the handle, and insert a pillar into the hole of the handle to fasten a complementary groove disposed on the circumferential surface of the air bushing, which complicates the manufacturing process, increases the cost and also spoils the structure of the pneumatic tool that may give rise to a leakage of the pressurized gas.